> ## Documentation Index
> Fetch the complete documentation index at: https://www.marqeta.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# August 2026 UX Toolkit Release Notes

> Release notes for the UX Toolkit: new features, enhancements, fixed issues, and breaking changes in each version.

To follow new UX Toolkit release notes with RSS, subscribe to the current release notes feed:

`https://www.marqeta.com/docs/developer-guides/ux-toolkit-release-notes/rss.xml`

**Breaking changes**

## Cardholder sign-in now requests access tokens from your dedicated authentication service by default

**Version:** 2.0.0

**Release date:** 2026-08-12

Action required

Breaking change

> [!WARNING]
>
> Upgrading to version 2 of the UX Toolkit requires migrating to dedicated OAuth.

Cardholder sign-in now requests access tokens from your program's dedicated authentication service by default, instead of the UX Toolkit API host. If your program has not been set up for dedicated authentication yet, pass `useDedicatedOauth: false` in your authentication parameters to keep the previous behavior while you complete setup. See [How to migrate UX Toolkit SDK to dedicated OAuth](https://www.marqeta.com/docs/developer-guides/KnowledgeBase/How-to-migrate-to-dedicated-OAuth.md) for the full migration steps.

**New features**

## Standard Bearer token authentication

**Version:** 1.21.0

**Release date:** 2026-08-03

The SDK now sends access tokens using the standard `Authorization: Bearer` scheme, aligning UX Toolkit authentication with common OAuth 2.0 conventions and making it easier to integrate with auth tooling that expects a standard Bearer header.

## Optional dedicated OAuth endpoint for minting access tokens

**Version:** 1.21.0

**Release date:** 2026-08-03

`bootstrap()` now accepts an optional `useDedicatedOauth` flag. Set it to `true` to mint access tokens from the Marqeta dedicated OAuth endpoint, giving your integration an isolated path for token issuance.

This flag defaults to `false`, so existing integrations continue to work without any changes until you choose to opt in.

## New X-Source-Client header for request diagnostics

**Version:** 1.21.0

**Release date:** 2026-08-03

The SDK now sends an `X-Source-Client` header on outbound API requests, identifying the SDK type, platform, and version. This gives Marqeta Support more context when helping you troubleshoot integration issues, reducing back-and-forth when diagnosing request-level problems.

**Enhancements**

## SDK version in request diagnostics now reflects the Web SDK release version

**Version:** 2.0.0

**Release date:** 2026-08-12

The SDK version reported in request diagnostics is now the release version of the Web SDK itself. It matches the version you pin and see in these release notes, instead of an internal package version.

**Bug fixes**

## Version 1.21.1

**Release date:** 2026-08-04

* Fixed an issue introduced in the previous release where components could remain stuck loading for integrations whose authentication endpoint restricts which request headers it accepts.

**No customer-facing changes**

## Version 2.0.2

**Release date:** 2026-08-27

This release contains infrastructure improvements and backend issue fixes only.

## Version 2.0.1

**Release date:** 2026-08-13

This release contains infrastructure improvements and backend issue fixes only.


## Related topics

- [January 2026 UX Toolkit Release Notes](https://www.marqeta.com/docs/developer-guides/ux-toolkit-release-notes/2026-01.md)
- [March 2026 UX Toolkit Release Notes](https://www.marqeta.com/docs/developer-guides/ux-toolkit-release-notes/2026-03.md)
- [April 2026 UX Toolkit Release Notes](https://www.marqeta.com/docs/developer-guides/ux-toolkit-release-notes/2026-04.md)
- [May 2026 UX Toolkit Release Notes](https://www.marqeta.com/docs/developer-guides/ux-toolkit-release-notes/2026-05.md)
- [June 2026 UX Toolkit Release Notes](https://www.marqeta.com/docs/developer-guides/ux-toolkit-release-notes/2026-06.md)